Linear frequency modulation continuous wave radar sensitivity frequency control method

Abstract

The invention discloses a linear frequency modulation continuous wave radar sensitivity frequency control method. The method is realized in a way that: a second-order band elimination filter is used at the intermediate frequency of a receiver to simulate the echo attenuation characteristic of the target; the second-order band elimination filter is used for reducing the sensitivity of the receiverat short range so as to prevent the short range clutter from saturating the receiver, and used for keeping the receiver at the original gain and sensitivity at long range so as to ensure the acquisition and identification of a small target; the second-order band elimination filter is realized by using an LC network; the center frequency of the band elimination filter is the intermediate frequencyof the receiver of the radar system; and the 3 dB bandwidth is determined according to the frequency modulation slope and the action range of the signal transmitted by the radar, and is twice of the 3dB bandwidth corresponding to one third of the maximum action range. The invention has the advantages of simple circuit form and convenient implementation. The test indicates that when the target range is within 10 Km, the amplitude attenuation of the target echo signal is about 46 dB, and the attenuation per frequency octave is about 12 dB.

Description

technical field [0001] The invention belongs to the application field of electronic technology, and relates to a control method, in particular to a linear frequency modulation continuous wave radar sensitivity frequency control method. Background technique [0002] The linear frequency modulated continuous wave (LFMCW) radar receiver outputs the target echo intermediate frequency beat signal amplitude and is inversely proportional to the fourth power of the distance from the radar to the target. Therefore, as the distance increases, the signal amplitude decays rapidly, and the target size changes , which requires the receiver to have a large dynamic range. That is, long-distance small targets can be detected, while short-distance large targets will not be saturated. In response to this problem, the concept of Sensitivity Frequency Control (SFC) was proposed and studied. In the continuous wave system radar, the relationship between the beat frequency of the echo signal and t...

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Problems solved by technology

In response to this problem, the concept of Sensitivity Frequency Control (SFC) was proposed and studied. In the continuous wave system radar, the relationship between the beat frequency of the echo signal and the distance of the target can be used to perform dynamic control in the frequency domain. Compression, according to the radar distance equation, the echo signal power is inversely proportional to the fourth power of the target distance (beat signal frequency in LFMCW radar). Weak, but the beat signal frequency is high. The SFC circuit design requires that the in-band amplitude-frequency characteristics generally rise approximately at a slope of 12dB / octave. Currently, there are some problems in the implementation of band-pass filters or digitally controlled attenuators. The band-pass filter cannot meet the requirement of 12dB / octave; the control is more complicated by using a numerically controlled attenuator

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